What is the limit for custom fields for each of the tabs and objects that your organization uses?

Answer options:

A.50
B.500
C.800
D.1000

Correct Answer: C 
 You can add custom fields for each of the tabs and objects that your organization uses, with a limit of 800 fields. 
Reference: 

https://trailhead.salesforce.com/en/content/learn/projects/customize-an-org-to-support-a-new-business-unit/modify-your-data-model